Brooke Weston

News Item

A Level practicals

Tuesday 20th November 2012 by C. Freeman

Sixth Formers spent three days conducting experiments and recording data for their A Level chemistry coursework. They chose an experiment, ordered equipment, conducted pre-trial tests and then carried out their experiment, gathering detailed data.

Head of Science Paul Knight said: ‘Most of them are varying concentrations to find out how the reaction mechanism actually works. There are a few who have made aspirin and will be analysing its purity against shop bought versions. There are a few clock reactions where iodine or bromine is produced at regular intervals. Students are studying the kinetics of that, looking at how the rate of reaction changes when they change concentrations or when they put a catalyst in.

‘They are using equipment such as the colorimeter that measures light passing through the solution and judging exactly when it has gone to a certain darkness. All of the students have got their reactions working and, once again, the technicians have done a fantastic job with all the equipment they have prepared.’

Student Connor McGrory’s experiment involved adding acid to sodium thiosulfate, measuring how fast it reacted and how the concentration affected the reaction speed.

Sam Shorten was using potassium iodide, starch, sodium thiosulphate and potassium peroxydisulfate to measure an iodine clock reaction: ‘I am changing the concentration of my reactants to find the rate of reaction, and then changing the temperature to work out the activation rate.’

Melissa Ward made aspirin and was testing its melting point. ‘It is made from 2 hydroxybenzoic acid and other ingredients. Aspirin’s melting point should be around 136, so if this sample is impure it will melt at a lower temperature.’

Teacher Mrs Hearne said: ‘The students are doing a variety of different practicals, all of which they have designed themselves. They plan and research the chemistry and carry out risk assessments. Afterwards they have to correct tables, draw graphs, and analyse and evaluate their work.’